The interruption of leprosy transmission is one of the main challenges for leprosy control programs since no consistent evidence exists that transmission has been reduced after the introduction of multidrug therapy. Leprosy, a disease caused by Mycobacterium leprae, particularly affects the less privileged parts of the population in countries where the disease is endemic. This intracellular bacillus is assumed not to be very pathogenic, most infections do not result in chronic disease but in skin lesions that heal spontaneously (13).
An assay device for the rapid detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera is presented. The sensitivity (85.8%) and specificity (93.6%) of the assay compared well (91.9% agreement) with those of an IgM enzyme-linked immunosorbent assay routinely used in the serodiagnosis of leptospirosis. The sensitivity of the assay varied with the stage of the disease. The assay uses stabilized components and is simply performed by the addition of serum and sample fluid to the sample well of the assay device. The assay is read after 10 min, and a positive result is obtained when staining of the test line is observed.As the clinical symptoms and signs of leptospirosis often are nonspecific, the disease is easily mistaken for other major infectious diseases. Manifestations of leptospirosis may vary, and different types of disease may be observed, from relatively mild influenza-like symptoms to severe disease with renal failure, liver impairment, and haemorrhage (Weil's syndrome). Meningismus and (aseptic) meningitis can be observed as well. Because of the wide variety of symptoms, leptospirosis is easily confused with many other fibril illnesses including haemorrhagic fevers, e.g., dengue fever (7). Laboratory testing to confirm the clinical diagnosis thus is essential for optimal treatment and patient management. The laboratory diagnosis of leptospirosis mainly depends on serology (8). The microscopic agglutination test (MAT) (5, 31) is considered the reference test for leptospirosis, but the enzyme-linked immunosorbent assay (ELISA) (2, 15-17, 19, 32, 34, 36) and a number of other tests including the immunofluorescent-antibody test (IFAT) (3), the slide agglutination test (9), the macrocapsule agglutination test (4), and the hemagglutination test (13,28,29) can be used as well. Drawbacks of the standard diagnostic assays like MAT, ELISA, and IFAT are that they are not very easy to perform, require special and expensive equipment, depend on the availability of electricity and refrigeration, or can be applied only by trained personnel. Hence, these assays are available only in a few specialized laboratories. MAT, which is considered the reference test for leptospirosis, is rarely performed by routine diagnostic laboratories.Leptospirosis has been reported from countries all over the world (1). Sporadic cases of leptospirosis may occur in countries with moderate climates. The disease, however, can be endemic in countries with wet and warm climates. People living under poor socioeconomical and hygienic conditions are at particular risk of getting the disease. Outbreaks have been reported (6, 11, 12, 14, 20-23, 27, 30, 33). Most people at risk cannot depend on health care facilities supported by laboratories capable of performing the more complicated standard laboratory assays. We previously developed a dipstick assay for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human sera (10,20,(24)(25)(26)35). This assay can be used outside the specialized laboratory and may e...
We studied a dipstick assay for the detection of Leptospira-specific immunoglobulin M (IgM) antibodies in human serum samples. A high degree of concordance was observed between the results of the dipstick assay and an IgM enzyme-linked immunosorbent assay (ELISA). Application of the dipstick assay for the detection of acute leptospirosis enabled the accurate identification, early in the disease, of a high proportion of the cases of leptospirosis. Analysis of a second serum sample is recommended, in order to determine seroconversion or increased staining intensity. All serum samples from the patients who were confirmed to be positive for leptospirosis by either a positive microscopic agglutination test or a positive culture but were found to be negative by the dipstick assay were also judged to be negative by the IgM ELISA or revealed borderline titers by the IgM ELISA. Some cross-reactivity was observed for sera from patients with diseases other than leptospirosis, and this should be taken into account in the interpretation of test results. The dipstick assay is easy to perform, can be performed quickly, and requires no electricity or special equipment, and the assay components, a dipstick and a staining reagent, can be stored for a prolonged period without a loss of reactivity, even at elevated temperatures.
Abstract. Among the many reported applications of the detection of antibodies to phenolic glycolipid-I (PGL-I) of Mycobacterium leprae, in particular, the use of seroprevalence as an indicator of the magnitude of the leprosy problem may turn out to be very useful in leprosy control programs. An operational function of serology within the leprosy control services requires a simple test system. We have developed a simple dipstick assay for the detection of antibodies to PGL-I and compared its performance with that of an ELISA. A high degree of agreement (97.2%) was observed between the ELISA and the dipstick assay when tested on 435 sera; the agreement beyond chance (Kappa value) was 0.92. No significant difference was found between the dipstick assay and the ELISA when seropositivity rates obtained in groups of leprosy patients, household contacts, and controls were compared. The interpretation of the dipstick results as positive or negative was unequivocal, as illustrated by the high agreement between different persons reading the test (Kappa values Ͼ 0.88). Storage of the only reagents required, the dipsticks and the stabilized detection reagent, up to three weeks under tropical conditions of high temperatures, high humidity, and exposure to light, did not influence the results of the assay. The dipstick assay described here is an easy-toperform method for the detection of IgM antibodies to PGL-I of M. leprae; it does not require any special equipment and the highly stable reagents make the test robust and suitable for use in tropical countries. An internal control validates the performance of the assay. This dipstick assay may be the method of choice for epidemiologic mapping of leprosy.Leprosy, caused by Mycobacterium leprae, is a disease that at present has a registered prevalence of 1.3 million people in the world currently on anti-leprosy chemotherapy, but the estimated number of cases in the world reaches about 1.8 million.
Leptospirosis is an often severe disease which requires prompt treatment. Laboratory testing is required to reach a valid diagnosis. An agglutination assay for the detection of Leptospira‐specific antibodies consisting of individually wrapped agglutination cards containing a stable, dried detection reagent is evaluated. The assay is simply performed by suspending the dried reagent with a drop of serum. The result is obtained within 30 s. The sensitivity of the assay varied with the stage of the disease and was 72.3% for samples collected during the first 10 days of the illness and 88.2% for samples collected at a later stage. The specificity was 93.9% and 89.8%, respectively. These characteristics make the test ideal for use in areas where the disease is common and where laboratory support is not routinely available.
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